The present invention relates to a pipe for circulating warm water, and more particularly to a warm water circulating pipe having excellent durability and oxygen impermeability.
As warm water pipes suitable for use in central heating, particularly floor heating installations by means of circulation of warm water, pipes made of iron or copper are widely used.
Recently, however, pipes made of plastics such as polyethylene, polypropylene and polybutene have been used more often in the place of pipes made of iron because of price and execution.
In a case of using such a plastic pipe, a metal device, such as a heat exchanger or a pump which is introduced the pipe, is corroded. It can be mainly considered that the corrosion is caused by oxygen which is introduced in warm water flowing through the pipe, because of the poor oxygen impermeability of the pipe.
Japanese Unexamined Patent Publication No. 61-83035 proposes, for improving the above-mentioned defect, a pipe made of a laminate comprising a layer of a composition comprising a hydrolyzed ethylene-vinyl acetate copolymer, or a pipe made of a laminate comprising a layer of a composition comprising a hydrolyzed ethylene-vinyl acetate copolymer and a substituted phenol compound. However, the above-mentioned defect is not sufficiently improved according to the proposal.
An object of the present invention is to provide a pipe for circulating warm water, which is improved with respect to the above defect.
This and other objects of the present invention will become apparent from the following description.